1. Field of invention
The invention relates generally to a novel vehicle accessory device providing for improved traction to vehicle wheels, and particularly to an improved traction strip for automotive driving wheels, for enabling a vehicle to move away after standing on a snow covered or icy or muddy road surface.
2. Description of the Prior Art
During winter months vehicular traffic on various roads, highways and railroads is hampered and frequently coming to a halt because of hazardous weather conditions, i.e. slippery snow or icy surface, sliding mud etc. In the case of an automobile traveling on a snow covered highway, the automobile tires could not gain enough traction to move the vehicle from its standing or parking position, and the vehicle becomes immobilized or stranded.
Traction in a general sense relates to the act of pulling a load over a surface by overcoming the resistance to motion. In a traffic situation traction relate to the friction or resistance to slipping developed at the point of contact of a driven wheel and the road surface on which it rolls. Under ordinary driving conditions the torque delivered to the automobile wheels by the axle, presses the wheels against the road surface long enough to develop sufficient traction required for moving the vehicle.
However, under snowy or icy conditions the surface of the road is slippery and the vehicle wheels may not gain sufficient traction because of the low coefficient of friction involved. An additional contributory factor to lack of traction under these circumstances is the heat given off by the friction of the tires which melts the snow or ice on the road surface, the former becoming solidified and glazed and making the surface even more slippery.
This presents special driving hazards and causes numerous accidents which take their toll in human life and property.
In order to safeguard against these hazards, drivers have been using for many years various forms of chains which were mounted on individual tires to increase traction. Also special snow tires have been designed with particular gripping treads in order to gain added traction. However, these devices proved to be inefficient, expensive, cumbersome and inconvenient and worst of all detrimental and damaging to the road surface.
In recent years there has been an increasing demand for relatively inexpensive and efficient devices that would provide additional traction to vehicles in hazardous weather conditions. Attempts were made to meet this demand by devices such as those illustrated in U.S. Pat. No. 3,836,075 or 3,858,803 and others.
However, it is recognized that these well known traction devices are inefficient and have serious disadvantages. For example, one of these devices (U.S. Pat. No. 3,836,075) has sharply pointed projections provided on the upper side of the devices for engaging the vehicle tires. This feature could prove highly detrimental to the tires through wear and tear of the same. Also the lower side of the device facing the ground is provided with a far smaller number of projections for gripping the road surface as compared with the number of projections used to engage the tires. It would appear that under slippery and icy conditions, this device would not work effectively to provide the added traction required for moving the vehicle.
A major disadvantage lies in another known device (U.S. Pat. No. 3,858,803) providing for transverse openings in a traction mat. When the road is covered with a layer of snow or ice, the latter could fill in the openings in the mat and form a solid slippery surface which would render the mat ineffective in providing any added traction to the stranded vehicle.
Thus, the present invention provides for a traction device that would substantially eliminate the above disadvantages and would resolve the long standing problems arising from lack of sufficient traction to motor vehicles in hazardous weather conditions.